audiopolicy: fix shared mmap capture

Change default maxActiveCount for MMAP input profiles to 0 (unlimited)
to enable simultaneaous capture by several streams in shared mmap mode.

Bug: 72134552
Test: 'adb shell write_sine_callback -m3 -pl -s100 -x' and Plug headphones in and out.
Test: AAudio CTS tests

Change-Id: I8743c2a8afb043c20babf8716878e5ca44bd72a4